Officials are probing how a 51-year-old highway bridge came to collapse in the Italian port city of Genoa yesterday, killing at least 26 people and injuring 16 others as it sent dozens of vehicles tumbling into a heap of concrete and twisted steel.

Lost bushwalkers ate Twisties to survive cold night

Three bushwalkers lost in a Victorian state park overnight used rope, bark and reeds to build a makeshift shelter.

Kirri Ord, 21, her 12-year-old brother and her boyfriend, 24, had just half a bag of Twisties and some water between them during their night in the Lerderderg State Park.

They were found safe on Monday morning, almost 24 hours after they set off for what was expected to be a "nice, sunny walk before lunch" according to Ms Ord, but four hours into the trek panic set-in when the group realised they were lost.

The alarm was raised after they failed to return by 5pm on Sunday (AEST), prompting an overnight police and SES search.

The three, from Werribee in suburban Melbourne, were walked out on Monday morning.

Ms Ord told News Corp she was able to use survival skills she had learned as a Girl Guide and then a Scout to make a shelter.

"We had a bit of rope and then we had the reeds and stuff on the side of the river," she told reporters at the scene of the rescue.